19-46755610-C-T

Variant names:

• chr19-46755610-C-T
• rs28937905
• NM_024301.5:c.160C>T

Variant summary

Our verdict is Pathogenic. The variant received 27 ACMG points: 27P and 0B. PS1_Very_Strong PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_024301.5(FKRP):​c.160C>T​(p.Arg54Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000207 in 1,452,756 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Pathogenic in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R54Q) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: FKRP NM_024301.5 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 0.392
• Publications: 4 publications found

Genes affected

FKRP (HGNC:17997): (fukutin related protein) This gene encodes a protein which is targeted to the medial Golgi apparatus and is necessary for posttranslational modification of dystroglycan. Mutations in this gene have been associated with congenital muscular dystrophy, cognitive disability, and cerebellar cysts. Several alternatively spliced transcript variants of this gene have been described, but the full-length nature of some of these variants has not been determined. [provided by RefSeq, Oct 2008]

FKRP Gene-Disease associations (from GenCC):

• autosomal recessive limb-girdle muscular dystrophy type 2I

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, Orphanet, Labcorp Genetics (formerly Invitae), Ambry Genetics
• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A5

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, G2P, Ambry Genetics
• muscular dystrophy-dystroglycanopathy type B5

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Myriad Women’s Health, Labcorp Genetics (formerly Invitae)
• myopathy caused by variation in FKRP

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• congenital muscular dystrophy with cerebellar involvement

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy with intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy without intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscle-eye-brain disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscular dystrophy-dystroglycanopathy, type A

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 27 ACMG points.

• PS1: Transcript NM_024301.5 (FKRP) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar as 3339462
• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_024301.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr19-46755611-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1524557.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 46 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 1.8498 (below the threshold of 3.09). Trascript score misZ: -2.4986 (below the threshold of 3.09). GenCC associations: The gene is linked to autosomal recessive limb-girdle muscular dystrophy type 2I, muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A5, congenital muscular dystrophy with intellectual disability, muscular dystrophy-dystroglycanopathy, type A, muscle-eye-brain disease, congenital muscular dystrophy with cerebellar involvement, myopathy caused by variation in FKRP, muscular dystrophy-dystroglycanopathy type B5, congenital muscular dystrophy without intellectual disability.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.953
• PP5: Variant 19-46755610-C-T is Pathogenic according to our data. Variant chr19-46755610-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 4228.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FKRP	NM_024301.5	c.160C>T	p.Arg54Trp	missense_variant	Exon 4 of 4	ENST00000318584.10	NP_077277.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FKRP	ENST00000318584.10	c.160C>T	p.Arg54Trp	missense_variant	Exon 4 of 4	1	NM_024301.5	ENSP00000326570.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00 AC: 0 AN: 232120 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000207 AC: 3 AN: 1452756 Hom.: 0 Cov.: 32 AF XY: 0.00000277 AC XY: 2 AN XY: 722400

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33328

American (AMR) AF: 0.00 AC: 0 AN: 44066

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25920

East Asian (EAS) AF: 0.00 AC: 0 AN: 39386

South Asian (SAS) AF: 0.00 AC: 0 AN: 85206

European-Finnish (FIN) AF: 0.0000201 AC: 1 AN: 49712

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1109330

Other (OTH) AF: 0.00 AC: 0 AN: 60046

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.055673), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2I Pathogenic:3

Feb 23, 2023

3billion

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is not observed in the gnomAD v2.1.1 dataset. The variant is located in a mutational hot spot and/or well-established functional domain in which established pathogenic variants have been reported. In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.91; 3Cnet: 0.58). Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000004228 / PMID: 14523375). Different missense changes at the same codon (p.Arg54Gln, p.Arg54Gly) have been reported to be associated with FKRP related disorder (ClinVar ID: VCV001524557 / PMID: 27439679, 33200426). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -

May 30, 2018

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Jan 01, 2004

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Autosomal recessive limb-girdle muscular dystrophy Pathogenic:1

Jul 18, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: FKRP c.160C>T (p.Arg54Trp) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The frequency data for this variant in gnomAD is considered unreliable, as metrics indicate poor data quality at this position. c.160C>T has been reported in the literature in multiple individuals affected with Limb-Girdle Muscular Dystrophy, Autosomal Recessive (example: Harel_2004). These data indicate that the variant is very likely to be associated with disease. The following publication has been ascertained in the context of this evaluation (PMID: 14523375). ClinVar contains an entry for this variant (Variation ID: 4228). Based on the evidence outlined above, the variant was classified as pathogenic. -

Walker-Warburg congenital muscular dystrophy Pathogenic:1

Dec 05, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 54 of the FKRP protein (p.Arg54Trp). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with limb-girdle muscular dystrophy (PMID: 14523375, 30003095). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 4228). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt FKRP protein function with a positive predictive value of 80%. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.61
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.83	.;D;.;.;.;D;.;.;.;.;.;.;.;.;T
Eigen	Benign	0.18
Eigen_PC	Benign	0.11
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.97	D;.;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.77	D
MetaRNN	Pathogenic	0.95	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.7	.;L;.;.;.;L;.;.;.;.;.;.;.;.;.
PhyloP100		0.39
PrimateAI	Pathogenic	0.91	D
PROVEAN	Uncertain	-4.0	.;D;.;.;.;D;.;.;.;.;.;.;.;.;.
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0040	.;D;.;.;.;D;.;.;.;.;.;.;.;.;.
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
Polyphen		1.0	.;D;.;.;.;D;.;.;.;.;.;.;.;.;.
Vest4		0.79
MutPred		0.83		Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);Gain of catalytic residue at L52 (P = 0.0031);
MVP		0.98
MPC		1.7
ClinPred		0.98	D
GERP RS		3.6
Varity_R		0.60
gMVP		0.95
Mutation Taster		=8/92	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs28937905; hg19: chr19-47258867; COSMIC: COSV59360232; COSMIC: COSV59360232;